1. Field of the Invention
This invention relates to various applications and concepts useful in the production of soft trim components such as typically found in the interior passenger compartment region of vehicles. More particularly, the invention relates to the use of a closed cell foam material, such as EVA, in the formation of seating, console and sun visor type components in a motor vehicle. Throughout this document, the terms “EVA” and “closed cell foam” are intended to be understood as generally synonymous.
2. Discussion
EVA (ethylene-vinyl acetate copolymer resin) is a petroleum-based foam product commercially available under various trade names, including but not limited to Levirex and PolyCell. EVA polymers have been used to form various consumer grade articles in an injection molding or extrusion process. A particular advantage of closed cell foam materials (like EVA) resides in the fact that EVA polymers become cross-linked during the molding process, or separate cooking process, which results in a very stable part. Due to the properties of EVA materials, it is typical for the molded part to rapidly expand upon mold separation, thereby usually resulting in a self-ejecting part. As the molded part cools, it shrinks and typically returns to an as-molded (or scaled design) size.
Known consumer applications of EVA molded products include clog-style shoes, clothing items, boot inserts, tires, and numerous other applications. The self-skinning foam creates a single-material finished part directly out of the mold. After molding, EVA material can be sewn using traditional machinery. Heating EVA and other post-forming techniques allow for custom fit opportunities.
Some prior art applications have taken advantage of the substantially expanded condition of an EVA part immediately after it is removed from a mold. For example, the prior art has taught to manufacturer light duty tires from an EVA compound. Such light duty tires have a substantially solid annular configuration with a tread portion disposed about the outer periphery. Prior to cooling, a wheel hub rim is inserted inside the annular tire and held there until the molded EVA portion cools and shrinks to a snug fit over the hub. In this manner, the EVA tire becomes permanently installed by way of mechanical lock, having hot shrunk into its final assembled condition on the hub.
Other uses of EVA materials have also been proposed, including the use in vehicular seat applications such as depicted in FIG. 3 of the accompanying drawings. Here, the so called “Metacar” product launched in Italy in 2006 includes bucket seat assemblies in which some of the interior soft trim portions of the seat and backrest have been manufactured from EVA molded compounds. In another example, U.S. publication number 2004/0155512 depicts a vehicle seat assembly in which certain soft trim portions may be fabricated from a foamed product of various sorts, one selection of which being an EVA material. In this example, the foamed product (e.g., EVA) is over-molded about the frame and other structural portions of the seat assembly. This over-molding technique is referred to as “integral molding” and described in paragraph [0050] of that patent application.
Various needs exist within the vehicle interior field of endeavor, including the desire for simplified/reduced foam and trim development processes, reduced seat assembly times, improved craftsmanship, unique styling opportunities, easily cleaned exterior surfaces, stain resistant and antimicrobial surfaces, and soft and durable surfaces. While EVA products have been used to some extent within the interior passenger compartment of a motor vehicle, that use has not been well-developed nor has it taken full advantage of some unique characteristics found in EVA materials. Accordingly, there is a need to provide automobile manufacturers and automobile consumers with unique seating and interior trim solutions that combine the features and benefits of foam, trim and plastics in a single process. The resulting product must be easy to clean and resistant to spills and staining.